1. Field of the Invention
This invention relates to a method and apparatus for processing a read-out image. This invention particularly relates to a method and apparatus for processing a read-out image, wherein scanning means is moved for reciprocal scanning with respect to an image carrier, which carries image information thereon, and an image signal representing the image information is acquired.
2. Description of the Related Art
It has been proposed to use stimulable phosphors as radiation detecting materials in radiation image diagnosing systems. Specifically, energy from radiation carrying image information of an object is stored and recorded on a stimulable phosphor, which is contained in a stimulable phosphor layer of a stimulable phosphor sheet. The stimulable phosphor layer of the stimulable phosphor sheet, on which the radiation image information has been stored, is then exposed to an electromagnetic wave acting as stimulating rays, which cause the stimulable phosphor to emit light in proportion to the amount of energy stored on the stimulable phosphor during its exposure to the radiation. The light emitted by the stimulable phosphor, upon stimulation thereof, is photoelectrically detected and converted into a digital image signal. The digital image signal is then processed and used for the reproduction of the radiation image information of the object as a visible image on a recording material.
Also, it has been proposed to use stimulable phosphors as radiation detecting materials in autoradiography image detecting systems. Specifically, a substance imparted with a radioactive label is administered to an organism, and the organism or part of a tissue of the organism is taken as a sample. The sample and a stimulable phosphor sheet provided with a stimulable phosphor layer are superposed one upon the other for a predetermined length of time, and energy from the radiation emitted by the radioactive label contained in the sample is thus stored on the stimulable phosphor contained in the stimulable phosphor layer of the stimulable phosphor sheet. The stimulable phosphor layer of the stimulable phosphor sheet, on which the radiation image information of the sample has been stored, is then exposed to an electromagnetic wave acting as stimulating rays, which cause the stimulable phosphor to emit light in proportion to the amount of energy stored on the stimulable phosphor during its exposure to the radiation. The light emitted by the stimulable phosphor, upon stimulation thereof, is photoelectrically detected and converted into a digital image signal. The digital image signal is then processed and used for the reproduction of the radiation image information of the sample as a visible image on a recording material. The autoradiography image detecting systems are disclosed in, for example, Japanese Patent Publication Nos. 1(1989)-60782, 1(1989)-60784, and 4(1992)-3952.
Further, it has been proposed to use stimulable phosphors as light detecting materials in chemiluminescence image detecting systems, the stimulable phosphors having the characteristics such that the stimulable phosphors absorb and store energy from light during exposure to the light and, when the stimulable phosphors are then stimulated by an electromagnetic wave having wavelengths falling within a specific wavelength range, the stimulable phosphors emit light in proportion to the amount of energy stored on the stimulable phosphors during the exposure of the stimulable phosphors to the light. Specifically, a biopolymer whose protein sequence, nucleic acid sequence, or the like, has been fixed is selectively labeled with a labeling substance capable of producing chemiluminescence when being brought into contact with a chemiluminescence substrate. The biopolymer having thus been selectively labeled with the labeling substance capable of producing the chemiluminescence is then brought into contact with the chemiluminescence substrate. Also, energy from the chemiluminescence having wavelengths falling within the visible light wavelength range, which chemiluminescence is produced by the labeling substance when the labeling substance is thus brought into contact with the chemiluminescence substrate, is stored on the stimulable phosphor contained in the stimulable phosphor layer of the stimulable phosphor sheet. Thereafter, the stimulable phosphor layer of the stimulable phosphor sheet, on which the chemiluminescence image information of the biopolymer has been stored, is then exposed to an electromagnetic wave acting as stimulating rays, which cause the stimulable phosphor to emit light in proportion to the amount of energy stored on the stimulable phosphor during its exposure to the chemiluminescence. The light emitted by the stimulable phosphor, upon stimulation thereof, is photoelectrically detected and converted into a digital image signal. The digital image signal is then processed and used for the reproduction of the chemiluminescence image information of the biopolymer as a visible image on a recording material. The chemiluminescence image detecting systems are disclosed in, for example, U.S. Pat. No. 5,028,793 and British Patent Publication GB No. 2,246,197A.
Furthermore, it has been proposed to use stimulable phosphors as electron beam detecting materials in electron microscope image detecting systems, the stimulable phosphors having the characteristics such that the stimulable phosphors absorb and store energy from an electron beam during exposure to the electron beam and, when the stimulable phosphors are then stimulated by an electromagnetic wave having wavelengths falling within a specific wavelength range, the stimulable phosphors emit light in proportion to the amount of energy stored on the stimulable phosphors during the exposure of the stimulable phosphors to the electron beam. Specifically, the electron beam is irradiated to a metal sample or a nonmetal sample, and an electron beam diffraction image or an electron beam transmission image of the sample is detected. The thus detected image is utilized for an element analysis, a sample composition analysis, a sample structure analysis, and the like. Alternatively, the electron beam is irradiated to an organism tissue, and an image of the organism tissue is detected.
Also, it has been proposed to use stimulable phosphors as radiation detecting materials in radiation diffraction image detecting systems, the stimulable phosphors having the characteristics such that the stimulable phosphors absorb and store energy from radiation during exposure to the radiation and, when the stimulable phosphors are then stimulated by an electromagnetic wave having wavelengths falling within a specific wavelength range, the stimulable phosphors emit light in proportion to the amount of energy stored on the stimulable phosphors during the exposure of the stimulable phosphors to the radiation. Specifically, with the radiation diffraction image detecting systems, the radiation is irradiated to a sample, and a radiation diffraction image of the sample is detected. The thus detected image is utilized for a sample structure analysis, and the like.
The electron microscope image detecting systems and the radiation diffraction image detecting systems described above are disclosed in, for example, Japanese Unexamined Patent Publication Nos. 59 (1984)-15843 and 61(1986)-93538, and U.S. Pat. No. 4,889,990.
The aforesaid various systems utilizing the stimulable phosphor sheets as the image detecting materials have the advantages in that chemical processing, such as development processing, need not be performed as in cases where photographic film is used. Also, the aforesaid various systems utilizing the stimulable phosphor sheets as the image detecting materials have the advantages in that various kinds of image processing are capable of being performed on the obtained image signals, and desired visible images are capable of being reproduced from the processed image signals. Further, the aforesaid various systems utilizing the stimulable phosphor sheets as the image detecting materials have the advantages in that quantitative analyses are capable of being performed by use of computers.
Further, fluorescence image detecting systems utilizing fluorescent substances as labeling substances in lieu of radioactive labeling substances in the autoradiography image detecting systems have heretofore been known. With the fluorescence image detecting systems, analyses of gene sequences and gene expression levels, separation and identification of proteins, and evaluation of molecular weights and characteristics of proteins are capable of being performed in accordance with information obtained by reading out fluorescence images. Specifically, for example, after a fluoro chrome has been added to a liquid containing a plurality of DNA fragments to be subjected to electrophoresis, electrophoresis of the plurality of the DNA fragments may be performed on a gel support. Alternatively, electrophoresis of a plurality of DNA fragments may be performed on a gel support containing a fluoro chrome. As another alternative, after electrophoresis of a plurality of DNA fragments has been performed on a gel support, the DNA fragments having been subjected to the electrophoresis maybe leveled with a fluoro chrome by, for example, a process for dipping the gel support in a liquid containing the fluoro chrome, the fluoro chrome may then be excited with excitation light to produce fluorescence, the thus produced fluorescence may be detected, and a fluorescence image may thereby be formed. In accordance with the thus formed fluorescence image, a DNA distribution on the gel support is capable of being detected.
As a further alternative, with the fluorescence image detecting systems, after electrophoresis of a plurality of DNA fragments has been performed on a gel support, the DNA fragments having been subjected to the electrophoresis may be denatured. Thereafter, at least part of the denatured DNA fragments may be transcribed to a transcription support, such as nitrocellulose, with a Southern blotting technique. The denatured DNA fragments and a probe having been prepared by labeling a DNA or an RNA, which is complementary to a target DNA, with a fluoro chrome, may then be subjected to hybridization. In this manner, only a DNA fragment, which is complementary to the probe DNA or the probe RNA, is selectively labeled with the fluoro chrome. Thereafter, the fluoro chrome, with which the DNA fragment described above has been labeled, may be excited with the excitation light to produce the fluorescence, the thus produced fluorescence maybe detected, and a fluorescence image may thereby be formed. In accordance with the thus formed fluorescence image, a target DNA distribution on the transcription support is capable of being detected.
As a still further alternative, with the fluorescence image detecting systems, a DNA probe, which is complementary to a DNA containing a target gene and has been labeled with a labeling substance, may be prepared. The DNA probe and a DNA on a transcription support may then be subjected to hybridization. Also, an enzyme maybe subjected to binding with the complementary DNA having been labeled with the labeling substance, and the thus bound enzyme may then be brought into contact with a fluorescence substrate in order to convert the fluorescence substrate into a fluorescent substance, which is capable of producing the fluorescence. Thereafter, the fluorescent substance may be excited with the excitation light to produce the fluorescence, the thus produced fluorescence maybe detected, and a fluorescence image may thereby be formed. In accordance with the thus formed fluorescence image, a target DNA distribution on the transcription support is capable of being detected.
The fluorescence image detecting systems have the advantages in that a radioactive substance need not be used, and the gene sequences, and the like, are capable of being detected in a simple manner.
The autoradiography image detecting systems, the chemiluminescence image detecting systems, the electron microscope image detecting systems, the radiation diffraction image detecting systems, and the fluorescence image detecting systems described above are utilized for the same purposes of use. Therefore, there has been proposed an image read-out apparatus capable of being utilized commonly for the autoradiography image detecting systems, the chemiluminescence image detecting systems, the electron microscope image detecting systems, the radiation diffraction image detecting systems, and the fluorescence image detecting systems described above.
The image read-out apparatus proposed for use in the systems described above comprises an optical head for irradiating the stimulating rays (or the excitation light) to the image carrier, such as the stimulable phosphor sheet provided with the stimulable phosphor layer, the transcription support containing the sample labeled with the fluorescent substance, or the gel support containing the sample labeled with the fluorescent substance, and collecting the light emitted by the image carrier, such as the light, which is emitted by the stimulable phosphor contained in the stimulable phosphor layer when the stimulable phosphor is stimulated by the stimulating rays, or the fluorescence, which is produced by the fluorescent substance for the labeling of the sample when the fluorescent substance is excited by the excitation light. In order to scan the image carrier, the optical head is capable of being moved in two dimensional directions along a plane parallel with the image carrier.
Both the stimulating rays for stimulating the stimulable phosphor and the excitation light for exciting the fluorescent substance will hereinbelow be referred to as the stimulating rays.
Specifically, there has been proposed an image read-out apparatus, wherein an optical head is moved for reciprocal scanning with respect to an image carrier, which carries image information thereon, and in a main scanning direction and moved in a sub-scanning direction, which intersects with the main scanning direction, stimulating rays are irradiated through the optical head onto the image carrier, light, which is emitted by the image carrier when the image carrier is exposed to the stimulating rays, is collected by the optical head and received by photoelectric conversion means, such as a photomultiplier (hereinbelow referred to as the PMT) or a CCD image sensor, and an image signal, which represents the image information recorded on the image carrier, is acquired from photoelectric conversion of the emitted light performed by the photoelectric conversion means.
As a read-out technique with the image read-out apparatus described above, there has heretofore been known a read-out technique, wherein image signal components are acquired from the image carrier in each of a forward scanning stage and a backward scanning stage of the reciprocal scanning with the optical head. With the read-out technique, an image information acquisition start position, from which the acquisition of the image information is started, and an image information acquisition length, over which the acquisition of the image information is performed, are determined previously. Also, the position of an image acquiring region in the forward scanning stage, which region extends on the image carrier in the main scanning direction, and the position of an image acquiring region in the backward scanning stage, which region extends on the image carrier in the main scanning direction, are matched with each other with respect to the main scanning direction. In this manner, forward scanning image signal components are acquired in the forward scanning stage, and backward scanning image signal components are acquired in the backward scanning stage.
Specifically, with the read-out technique described above, a position, which is spaced away by the image information acquisition length in the main scanning direction from the image information acquisition start position, is taken as an image information acquisition end position. Also, the image information acquisition start position in the forward scanning stage and the image information acquisition end position in the backward scanning stage are set so as to coincide with each other with respect to the main scanning direction, such that the position of the image acquiring region in the forward scanning stage and the position of the image acquiring region in the backward scanning stage coincide with each other with respect to the main scanning direction.
However, in cases where the image information acquisition start position in the forward scanning stage or the backward scanning stage shifts in the main scanning direction from the predetermined position, which has been set previously, due to a change in temperature, a change with the passage of time, or the like, the problems described below occur. Specifically, the image information acquisition start position in the forward scanning stage and the image information acquisition end position in the backward scanning stage do not coincide with each other with respect to the main scanning direction. Also, the image information acquisition start position in the backward scanning stage and the image information acquisition end position in the forward scanning stage do not coincide with each other with respect to the main scanning direction. Therefore, in such cases, the forward scanning image signal components and the backward scanning image signal components are acquired respectively from the image acquiring region on the image carrier in the forward scanning stage and the image acquiring region on the image carrier in the backward scanning stage, which regions do not coincide with each other with respect to the main scanning direction. The forward scanning image signal components and the backward scanning image signal components having thus been acquired are utilized for reproduction and displaying of the image information, which are performed in accordance with predetermined setting such that the image information acquisition start position in the forward scanning stage and the image information acquisition end position in the backward scanning stage coincide with each other with respect to the main scanning direction. Accordingly, in the displayed image, a forward scanning image display region, which is represented by the forward scanning image signal components, and a backward scanning image display region, which is represented by the backward scanning image signal components, shift from each other in the main scanning direction. In such cases, values of pixels in the displayed image, which pixels are represented by the forward scanning image signal components and the backward scanning image signal components and are arrayed in the sub-scanning direction, take discontinuous values. Specifically, the difference between the values of the pixels become large. As a result, a contour, or the like, of the displayed image, which is formed with the forward scanning image display region represented by the forward scanning image signal components and the backward scanning image display region represented by the backward scanning image signal components, is blurred.
Also, in cases where the image information has been recorded with high contrast on the image carrier, it often occurs that the intensity of the light emitted by the image carrier changes markedly from a high intensity to a low intensity. In such cases, the photoelectric conversion means, which is receiving the emitted light of the high intensity and is performing the photoelectric conversion by producing many electrons or electric charges, cannot be reset quickly in accordance with the marked change in emitted light intensity. Therefore, a phenomenon often occurs such that the image signal components, which represent the intensities higher than the intensity of the received light, are acquired until the photoelectric conversion means is reset to a state in which the photoelectric conversion means is capable of accurately acquiring image signal components. The phenomenon described above is referred to as the trailing. In cases where the optical head, which has scanned a certain region emitting the light of the high intensity, successively moves beyond the certain region and scans a next region emitting the light of the low intensity, the training occurs in the image signal components, which are acquired when the optical head scans the next region described above. Therefore, the direction, in which the trailing occurs, varies for the forward scanning image signal components and the backward scanning image signal components. Accordingly, as in the cases described above, the problems occur in that the contour, or the like, of the displayed image, which is reproduced from the forward scanning image signal components and the backward scanning image signal components and represent the image information recorded on the image carrier, is blurred.
The problems described above occur commonly in cases where the read-out technique described above is applied to the autoradiography image detecting systems, the chemiluminescence image detecting systems, the electron microscope image detecting systems, the radiation diffraction image detecting systems, the fluorescence image detecting systems, and the like.